No, there are not. The Balance school trainers are Arthur Wethersfield(RavenWood), Alhazred(Krokotopia), and Niles(the Balance Tree), and a few other "hidden" trainers. The future spells you get from the Balance school will be from spell quests you will receive from your teacher. If you are not a Balance wizard, you can not learn any of the other spells after that point. The only way to get the other spells is if they're in treasure card form. There are also spells you can craft from the recipe vendor behind the Plague Oni in Shirataki Temple. There may also be a craftable balance spell behind the Indigo Giant in Avalon but I am unsure. Hope I helped

I have just got to level 42 are there any other balance teachers than the kroc

nope. all spells after level 42 are school-only quest spells that cannot be learned from trainers. professor alhazred will summon you when you meet the level and quest requirements for your next assignment.